Comparación de rasgos hidráulicos y de soporte entre fuste y rama de un bosque seco tropical (Bs-T)

Abstract

Tropical dry forests are the most threatened in the world ; in Colombia is only 8 % of its original coverage Bs- T. This ecosystem is characterized by its high degree of degradation , which makes it a fragile ecosystem conservation urgently . That is why this study aims to contribute to the knowledge of this ecosystem from the study of functional traits in order to predict responses to the rapid changes affecting these ecosystems , understanding the functional traits are morphological, physiological or phenological characteristics level agencies that relate to factors and / or operating processes of an ecosystem ( Diaz & Fitted , 2001). It is also the objective of the study is to understand the intra-individual and intra-specific variation in the anatomical trait wooden branches and trunk wood cores 19 species of tropical dry forest in Colombia. The study was conducted in a fragment of tropical dry forest, located in the Magdalena River Valley, in the towns of Nilo and Agua de Dios, Cundinamarca; two sites of 1 hectare each were selected; the wherein functional traits related to hydraulic driving and support in plants, specifically related traits were evaluated mechanical support: wood density, thickness and length of the fibers. As for the traits related to hydraulic conductivity: vessel diameter, diameter intervessel pits, length and density of vessels conducting they were evaluated. The evaluation was conducted from measuring these traits in wood cores taken in stem and branches. five replicates of each of the 10 species with the highest importance value of each site were taken; later, an exploratory analysis was performed from Box- plot diagrams and testing variance analysis nonparametric Kruskal-Wallis in the 5 individuals assessed by species; the correlation between traits was analyzed with a multivariate principal components analysis (PCA) and Spearman correlation; statistical tests were done with free software Infostat®. The results showed significant difference in measurements of traits between branches and wood cores in hydraulic and support traits. The length and thickness of fibers and wood density are higher in the stem and in terms of hydraulic traits the vessel diameter, length of vessels and pit diameter showed higher values in the stem, while the frequency of pores are greater in the branches. Additionally, wood density, present a similar pattern of variation and is a key trait in both functions evaluated, providing both the support function and water transport in the plant; Also, support traits are correlated positively with the hydraulic traits are geared toward safety, and inversely oriented features hydraulic water efficiency. Confirming that species with denser wood are more resistant to drought.